Characteristics of Patients With Bibrachial Amyotrophy Due to Spontaneous Spinal CSF Leaks

Spontaneous spinal CSF leaks cause intracranial hypotension (SIH) and may be complicated by bibrachial amyotrophy (BBA), but the clinical and radiographic features of this complication are not well characterized. The objective of this study was to identify the unique characteristics and outcomes of treatment in patients with SIH and BBA.

In this case-control study of patients with SIH complicated by BBA, 2 matched controls were selected per patient based on type of underlying leak (ventral vs lateral) and year of encounter. The patients were evaluated at a quaternary referral center between January 1, 2001, and June 30, 2024.

The study population consisted of 25 consecutive patients with SIH who had been suffering from BBA for a mean of 51 months. Compared with controls, men were overrepresented (80 vs 18%; p < 0.0001), while age at presentation was similar (p = 0.69). A history of orthostatic headache typical of SIH was reported by 16 of the 25 patients with BBA. Age at onset of SIH was earlier in those with BBA (25.9 years) compared with controls (40 years) (p = 0.0522). The mean interval between the onset of SIH and the onset of BBA was 13.2 years (range, 1 to 45 years). Muscle groups affected included the C5 to T1 myotomes. The anterior CSF collection was more than twice as thick in patients with BBA compared with controls (mean, 6.3 vs 2.9 mm) (p < 0.0001). Twenty-two patients underwent surgical closure of the CSF leak. BBA symptoms improved postoperatively in 13 of 18 patients who underwent surgical repair <10 years of BBA onset vs none of the 4 patients who underwent surgical repair >10 years of BBA onset or the 2 patients who did not undergo surgical repair (p = 0.007).

BBA due to SIH is rare, typically affects men, occurs years after SIH symptom onset, and is associated with a thick anterior extradural CSF collection on MRI. Our data suggest that surgical repair is low risk, durable, and should arrest or reverse motor impairment if performed within 10 years of BBA symptom onset, but more rigorous study designs are needed to address outcomes in these patients.